Yeah, leaving is my main issue. When I get pulled into something and I decide it's not relevant to me, I can close the conversation, but it'll reopen as soon as

Yeah, leaving is my main issue. When I get pulled into something and I decide it's not relevant to me, I can close the conversation, but it'll reopen as soon as anyone writes anything, so muting and having it pollute my conversation list is the only option. Can added people read previous messages, or are they only starting at the moment they enter?